Inside pipecutter

ABSTRACT

An inside pipecutter for cutting plastic pipe encased in concrete such as a drain pipe extending through a concrete floor including a rotatable mandrel having a plurality of radially movable cutters mounted therein and having an axially movable wedge for moving such cutters radially outwardly as the mandrel is rotated. The apparatus also includes a guide means for setting the depth of the cut-off of the pipe relative to the upper surface of the concrete floor through which the pipe extends.

United States Patent Kurtz 1 May 20, 1975 [541 INSIDE PIPECUTTER 1lognson i [76] Inventor: Arthur L. Kurtz, 4202 Little Berry, I 0 I Houston, Tex. 77018 FOREIGN PATENTS OR APPLICATIONS 22 Ffled; J 2 1973 9,203 6/1887 United Kingdom................... 30/106 [21] Appl' 374523 Primary ExaminerA1 Lawrence Smith 52 u s CI 30/106 30/103 2mm"! Examiner? T. fi l kl. Wl

ttorney, gent, or u'mrave ison [51] Int. Cl..... 823d 21/08; 823d 21/14; B26d 3/16 [58] Field of Search 30/103, 104, 105, 106,

30/107 108 [57] ABSTRACT An inside pipecutter for cutting plastic pipe encased in [56] References Cited concrete such as a drain pipe extending through a UNITED STATES PATENTS concrete floor including a rotatable mandrel having a 482,496 9/1892 Coppage 30/103 Mummy. l mmable cutters mwmed. herem 505 328 893 Pm l 4 I 0 M06 and having an axially movable wedge for moving such 6461722 I900 30/)6 cutters radially outwardly as the mandrel is rotated. 790,820 5/1905 Dozer 30/106 The apparatus also Includes a guide means for semng 802,215 10/1905 Johnson 30/104 the depth of the cut-off of the pipe relative to the 860,052 7/1907 McCormick..... 30/104 upper surface of the concrete floor through which the 943,323 12/1909 Sorensen 30/107 i t d 1,316,145 9/1919 Doyle 30/106 1,413,228 4/1922 King 30/107 5 Claims, 4 Drawing Figures 1 INSIDE PIPECLTTER BACKGROUND OF THE INVENTION lv Field of the Invention The present invention pertains to a rotatable inside pipecutter for cutting off the end of a PVC or other plastic pipe extending through a concrete slab or floor.

2. Description of the Prior Art Various prior art devices have been provided for cutting off plastic pipe in a concrete slab. However. such devices do not provide a means for cutting the upper edge of the pipe substantially parallel to the concrete slab on the first cut. but rather usually require that the stub of the plastic pipe protruding above the concrete slab be cut in a plane substantially parallel to the surface of the concrete and using the cut upper edge as a guide. the pipecutter then cuts a second time inside of the pipe and beneath the upper edge of the concrete slab.

SUMMARY OF THE INVENTION The present invention provides a new and improved rotatable inside pipecutter comprising a mandrel having one or more cutters mounted therein and movable radially outwardly as the mandrel is rotated for cutting the pipe and further. the invention includes adjustable guide means for setting the depth of the cutter in the PVC pipe relative to the upper surface of the concrete slab or floor through which the pipe protrudes to enable a cut to be made in the desired elevation relative to such upper surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a elevational view of the inside pipecutter apparatus of the present invention shown in place in a pipe in a concrete slab.

FIG. 2 is an isometric exploded view of the pipecutter of the present invention showing the cutter carriers and the wedge-shaped drive means and the mandrel:

FIG. 3 is a transverse sectional showing the assembly of the parts of the apparatus with the cutters in an extended position; and

FIG. 4 is a view partially in elevation and partially in section showing the cutters retracted into the mandrel.

DESCRIPTION OF THE PREFERRED EMBODIMENT The pipecutter apparatus of the present invention is designated generally P in FIG. I of the drawings. Such apparatus includes a mandrel M. a guide G and one or more cutter assemblies C which are rotated with the mandrel. A wedge-shaped cutter drive W shown in FIG. 2 of the drawings is provided for moving the cutters C radially inwardly and outwardly relative to the mandrel M. The guide G includes a pair oflegs L which support the mandrel M with the cutters C at a desired elevation relative to the upper surface S of the concrete C in which the pipe P is imbedded.

It will be appreciated that with this invention it makes no difference how far the upper end ofthe pipe P protrudes above the upper surface S of the concrete C so long as it is not so far as to engage the guide G and also. it does not make any difference whether the upper edge of the protruding section ofpipe P is straight. or jagged or cut at an angle as the pipe cutting apparatus of the present invention uses the upper surface of the concrete S as a reference for setting the depth of the cut by the cutters C and does not engage the upper surface of the protruding pipe P.

Considering now the apparatus of the present invention in more detail. the mandrel M comprises a large diameter body portion 10. an intermediate diameter body portion ll thereabove. and a reduced diameter body portion 12 adjacent to the upper end [3 for re ceiving thrust bearings 14 and the guide plate G. As shown. the mandrel is provided with a non-circular opening 17 extending through the intermediate diameter portion II for receiving the non-circular upper end of the wedge drive shaft 20 as will be described in detail hereinafter. Further, a rectangular opening I9 is provided in the larger diameter portion for receiving the drive wedge 22 of the wedge-shaped member W. Such rectangular portion is of a sufficient width in its larger dimension to accommodate the wedgeshaped drive head 22 and is of a sufficient distance in its narrower dimension so as to engage the opposite parallel sides 22a and 22b for guiding such wedge-shaped drive member as it moves axially of the mandrel M.

The mandrel M also includes in the preferred em bodiment illustrated in FIGS. 2, 3. and 4 of the drawings a pair of side windows or openings 24 through which the cutters C protrude for cutting the pipe or are retracted as shown in FIG. 4. In the preferred embodiment of the present invention. a pair of diametrically opposed cutters C are employed for cutting the pipe. However, it will be appreciated that other cutter arrangements may be used without departing from the spirit of the present invention.

As shown in FIGS. 2. 3 and 4 of the drawings. the wedge-shaped drive W comprises a longitudinally extending rectangular or noncircular shaft portion which engages the correspondingly rectangular or noncircular opening I7 extending through the upper portion 11 of the mandrel M for rotating the mandrel M and the cutters C. The lower end of the wedge-shaped drive member W comprises a wedge member 22 which includes a pair of downwardly and inwardly extending sides which are tapered toward the center line of the mandrel M. Such wedge-shaped member is provided with a blunt point 32 which engages a stop in the lower end of the mandrel 10 as will be described in detail hereinafter. The tapered sides 30 of the wedge drive head 22 are provided with a channel or lip portion 23 which engages a corresponding interlocking channel or lip portion 34 on each of the carrier blocks of the cutters C. Such interlocking flanges 34 and 23 cause the carrier blocks 40 to move radially inwardly and outwardly as the wedge drive head 22 is moved axially upwardly and downwardly in the mandrel M. The upper end of the wedge-shaped drive member W is provided with a circular neck portion 36 for connecting an electric drill or other drive apparatus for rotating the man drel M and the cutters C. It will be appreciated that the electric drill or other drive means connected to the neck 36 may also be used to move the shaft 20 upwardly and downwardly to thereby move the wedge block 22 so as to move the carriers 40 radially in and out of the windows or apertures 24 relative to the mandrel body 10.

A bottom plate 42 is provided in the lower end of the mandrel l0 and secured therein by suitable screws 44 or other suitable securing means. Such bottom plate includes a threaded stop member 46 which projects upwardly in the center of the body 10 for engaging the lower blunt end 32 of the wedge member 22 for providing a stop so as to limit the downward movement of the wedge body 22 and the outward movement of the cutter block 40. As shown. a downwardly and outwardly inclined shoulder 48 is provided on the inner surface of the mandrel adjacent the upper end of the rectangular bore l9 and a corresponding inclined surface 50 is provided on either side of the wedge block 22 to allow the wedge block to be moved upwardly so as to move the cutter carriers 40 inwardly in a retracted position such as shown in FIG. 4 of the drawings.

The cutter blocks 40 are provided with downwardly and inwardly tapered inner sides 60 on which the interlocking lip 34 is formed and are also provided with a transverse slot or opening 62 which extends in a plane substantially perpendicular to the axis 70 of such mandrel M. The cutter blades 66 are mounted on suitable pins 68 carried in the cutter housing 40 and extending transversely of the notch or opening 62. The cutter blades 66 are disc-shaped members having a sharpened circumferential edge that are mounted on the pins 68 so as to project outwardly beyond the outer end 40a of the wedge-shaped block 40.

STATEM ENT OF OPERATION In cutting the top portion out of a section of plastic pipe P' which extends through a concrete slab C and projects or protrudes thereabove as shown in FIG. 1 of the drawings, the pipe cutting apparatus of the present invention is positioned with the mandrel M inserted into the upper open end of the pipe P. The depth at which the cutters C are set is controlled by adjusting the height of the transverse member G of the legs L. With the cutters at the desired elevation. a power drill or other suitable drive device is secured to the neck 36 and actuated for rotating the drive shaft which in turn rotates the mandrel M relative to the gauge or cross member G and the legs L. As the wedge member W is moved downwardly during rotation it urges the cutter carriers 40 radially outwardly so as to cause the cutters 66 to protrude through the apertures or openings 24 and into cutting engagement with the interior surface of the pipe P. As the cutters 66 begin to cut. continued downward pressure on the wedge-shaped member W continues to urge the cutters radially outwardly until the pipe has been completely severed. Thereafter. the apparatus P is withdrawn from the severed end portion of the pipe P' by moving the noncircular drive means axially outwardly with respect to the mandrel M to thereby retract the cutter means back into the mandrel M.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size. shape. and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

I claim:

1. An inside pipecutter for cutting off plastic pipe encased in concrete at some desired elevation above or below the upper surface of the concrete comprising:

a. a rotatable mandrel adapted to be inserted into the upper open end of a section of plastic pipe embedded in concrete and protruding above the upper surface of such concrete;

b. guide means for supporting said rotatable mandrel adjacent its upper end with its lower end in the pipe. said guide means including a plurality of adjustable legs for supporting said mandrel at a desired elevation relative to the upper surface of the concrete;

c. cutter means carried by said rotatable mandrel and movable radially outwardly beyond the outer circumference of said mandrel and into engagement with the inner surface of the plastic pipe for cutting same;

d. means for rotating said mandrel;

e. drive means for urging said cutter means radially outwardly for cutting the pipe upon rotation of said mandrel, said drive means including a wedge shaped drive means; and

f. adjustable stop means in said mandrel for limiting downward movement of said wedge shaped drive means, said stop means being mounted for adjustment from the exterior of said mandrel.

2. The invention of claim 1 wherein:

said mandrel is a cylindrical member having a noncircular passage extending axially thereof and wherein said means for rotating said mandrel is a non-circular member carried in said non-circular passage.

3. The invention of claim 1 wherein:

said mandrel has a pair of openings on opposite sides thereof through which said cutter means are radially movable.

4. The invention of claim 1 including:

cutter carriage means and wherein said wedge shaped drive means includes a pair of inwardly and downwardly tapered surfaces for engaging corresponding tapered surfaces on said cutter carriage means.

5. The invention of claim 4 wherein:

said inwardly and downwardly inclined surfaces on said wedged shaped drive means and said cutter carriage means include interlocking channel means connecting said cutter carriage means and said wedge shaped drive means. 

1. An inside pipecutter for cutting off plastic pipe encased in concrete at some desired elevation above or below the upper surface of the concrete comprising: a. a rotatable mandrel adapted to be inserted into the upper open end of a section of plastic pipe embedded in concrete and protruding above the upper surface of such concrete; b. guide means for supporting said rotatable mandrel adjacent its upper end with its lower end in the pipe, said guide means including a plurality of adjustable legs for supporting said mandrel at a desired elevation relative to the upper surface of the concrete; c. cutter means carried by said rotatable mandrel and movable radially outwardly beyond the outer circumference of said mandrel and into engagement with the inner surface of the plastic pipe for cutting same; d. means for rotating said mandrel; e. drive means for urging said cutter means radially outwardly for cutting the pipe upon rotation of said mandrel, said drive means including a wedge shaped drive means; and f. adjustable stop means in said mandrel for limiting downward movement of said wedge shaped drive means, said stop means being mounted for adjustment from the exterioR of said mandrel.
 2. The invention of claim 1 wherein: said mandrel is a cylindrical member having a non-circular passage extending axially thereof and wherein said means for rotating said mandrel is a non-circular member carried in said non-circular passage.
 3. The invention of claim 1 wherein: said mandrel has a pair of openings on opposite sides thereof through which said cutter means are radially movable.
 4. The invention of claim 1 including: cutter carriage means and wherein said wedge shaped drive means includes a pair of inwardly and downwardly tapered surfaces for engaging corresponding tapered surfaces on said cutter carriage means.
 5. The invention of claim 4 wherein: said inwardly and downwardly inclined surfaces on said wedged shaped drive means and said cutter carriage means include interlocking channel means connecting said cutter carriage means and said wedge shaped drive means. 